Process for treating coal



Patented Nov. 22 1938' PATENT OFFICE rnocsss Fon TREATING COAL I IOliver M. Urbain and William B. Stemen, Columbus, Ohio, asaignors toCharles lLLewls, Harpster, Ohio No Drawing. Application ottom- 21, 1934,

- Serial No. 750,385

8 Claims. 01. 252-) This invention contemplates a process for treatingcoal and specifically relates to the provision of a process for thechlorination of coal.

Chlorinated coal is highly useful as a,,filteri ng 5 medium or purifyingagent in water purification processes, especially in the removal oforganic compounds therefrom. The present invention is directed to anovel and economic method of producinglclglorinated coal suitable forthese and ill other uses. The coal to be chlorinated may be sub-bituminous, bituminousor anthracite. The coal to be chlorinated is preferablyfirst powdered to pass ,through a screen of from '5 to mesh. Thechlorination of the coal is effected by passing chlorine gas through thecoal while the same is maintained at a temperature somewhat below 125 C.or the temperature at which the chlorine compounds decompose. Care isexercised to keep W the temperature below this critical point. Ofcourse, the temperature must be at least room temperature or above.

Catalysts are advantageously used in the chlorination process though thecoal can be chlorinated in the absence of catalysts. Suitable catalystsare such as iron, iodine, sulfur and lead. During the chlorinationperiod, the coal mass rises somewhat in temperature and hydrochloricacid gas and water vapor are copiously given off.

w Carbon oxides, hydrocarbons and chlorinated hydrocarbons are alsogiven oil in lesser amounts. The chlorination of the coal is effected inan apparatus possessing the capacity to withstand the action ofhydrochloric acid and to also withstand a moderate superatmosphericpressure of say up to 200 pounds per square inch. The process may beadvantageously carried out under superatmospheric pressure. Experienceteaches that'the finer the coal the higher the, temperature up to 125 C,and the higher the pressure that should be employed. A

longer time period of contact should be maintained for the finer coal.These factors all tend to produce a finished product having a high per-45 centage of chlorine. In some instances the finishedproduct containsas much as 71% of chlorine by weight. g

The percentage of chlorine in the finished product depends upon and canbe varied by controlling the following factors:

-. 1. Fineness of the coal.

2. Nature and kind of coal. I 3. Temperature of chlorination. v 4.Pressureof chlorination. -5. Time subjected to chlorination.

The chlorinated coal; when hard coal is used, has about the samehardness and is no less fragile than the original coal. The chlorinatedcoal, however, when soft coal is employed, is considerably harder thantheoriginal coal. 5

It is believed that the action of the chlorine on the mal maybeexpressed bythemfollowing fac tors:

l. The chlorine substitutes for hydrogen in the hydrocarbon part of thesd-called coal con- 1i?) glomerate.

2'. The chlorine oxidizes certain of the group ings and opens up thering structures.

3. The chlorine adds to the unsaturated points in the coal. i m

4. The chlorine renders the inactive inorganic constituents (coal ash)soluble andpermits their removal by water washing to open up the coalstructure and increase the active surface of the mass. v m

5. The chlorine activates the surface of the mass by shifting theadsorbed and absorbed ases.

The exact temperature below 125 0., the pressure and the time period oftreatment of the coal W with chlorine are all variable, depending uponthe character of the finished product desired. and can be readilyselected by trial tests. If the product is to be used as a filter theparticle size should be so controlled as to be between 5 mesh and 10 m)mesh. If the product is to be used as a treating reagent to be mixedwith the material treated,

it may be reduced to a fineness that will pass through a 40 mesh screen.The product may be water washed if desired. 35

To increase the activity of the chlorinated coal toward certain groupsof organic compounds, for. example, alcohols, aidehydes, ketones andorganic acids, it is advantageous to effect hydroxyiation of thechlorinated coal. This may be effected by treating the chlorinated coalwith an alkali such for example as sodium hydroxide or calciumhydroxide, it being understood that the hydroxides of the alkali metalsand alkaline earth metals are suitable for this purpose. Thehydroxylation may be carried out at temperatures up. to 100 C. Thereactions, of course, proceed faster at the higher temperatures.

The hydroxylation of the chlorinated coal may also be effected to lesserdegree by the action of steam or hot water. In either event, thehydroxylation is believed to be a result of the hydrolysis orsaponiflcation, or both, of the chlorinated coal. p

decompose, for a time period adequate to form a product rich in combinedchlorine, and subsequently effecting hydroxylation by treating withsteam thereby improving the sorptive properties of the chlorinated coal.

2. A process for the preparation of asorptive carbonaceous material foruse in water purification which comprises passing gaseous chlorinethrough powdered coal at a temperature below that at which the chlorinecompounds formed decompose, for a time period adequate to form a productrich in combined chlorine, and subsequently ei'lecting hydroxylation bytreating with hot water thereby improving the sorptive properties of thechlorinated coal.

3. A process for the preparation 01 a sorptive carbonaceous material foruse in water purificamamas cation which comprises passing gaseouschlorine through powdered coal" in the presence of a catalyst selectedfrom the group of iron, iodine, .sulphur and lead, at a temperaturebelow 125 C., for a time period adequate to form a product rich incombined chlorine, and subsequently eflecting hydroxylation by treatingwith hot water thereby improving the sorptive properties of thechlorinated coal.

6. A process for the preparation of a sorptive carbonaceous material foruse in water purification which comprises passing gaseous chlorinethrough powdered coal at a temperature below 125 C., for a time periodadequate to form a product rich in combined chlorine, and subsequentlyeilecting hydroxylation by washing with water containing in solution analkali metal hydroxide thereby improving the sorptive properties of thechlorinated coal.

7. A process for the preparation of a sorptive carbonaceous material foruse in water purification which comprises passing gaseous chlorinethrough powdered coal at a temperature below tion which compm gaseouschlorine -\125 0-, for 8. time Period adequate to form a throughpowdered coal at a temperature below 12555}, (one. time period adequateto form a product'rich in'jcomblnerLchlorine, and subsequently effectinghydroxylation by treating with hot water thereby improving the sorptiveprop-' erties of the chlorinated coal.

4. A process for the preparation of a sorptive carbonaceous material foruse in water purification which comprises passing gaseous chlorinethrough powdered coal under super-atmospheric pressures at a temperaturebelow 125? 0., for a time period adequate to form a product rich incombined chlorine, and subsequently effecting hydroxylation by treatingwith hot water thereby improving the sorptive properties of the chicrinated coal.

5. A process for the preparation of a sorptive carbonaceous material foruse in water purinproduct rich in combined chlorine, and subsequentlyeflecting hydroxylation by washing with water containing in solution analkaline earth metal hydroxide thereby improving the sorptive propertiesof the chlorinated coal,

8. A processfor the preparation of a sorptive carbonaceous material foruse in water purification which comprises passing gaseous chlorinethrough powdered coal at a temperature below 125 C., for a time periodadequate to form a product rich in combined chlorine, and subsequentlytreating with a reagent capable of efiecting hydroxylation byintroduction of hydroxyl' groups thereby improving-the sorptiveproperties of the chlorinated coal.

.WILLIAM R. STEMEN.

